c++ - Working with structure objects -

i have logic looks below (not actual code):

structureelement x;  in 1 1000      x.elem1 = 20;     x.elem2 = 30;     push(x std::vector)    end  

my knowledge x allocated memory once , existing values overwritten every iteration. also, 'x' pushed vector not affected subsequent iterations of pushing modified 'x'.

am right in observations?

is above optimal? want keep memory consumption minimal , not prefer using new. missing not using new?

also, pass vector , recieve reference it method.

and, if read vector elements back, right?

structure element xx = myvector.begin() print xx.elem1 print xx.elem2 

any optimizations or different ideas welcome.

am right in observations?

yes, if vector std::vector<structureelement>, in case keeps own copies if pushed in.

is above optimal?

it sub-optimal because results in many re-allocations of vector's underlying data buffer, plus unnecessary assignments , copies. compiler may optimize of assignments , copies away, there no reason, example, re-set elements of x in loop.

you can simplify this:

std:vector<structureelement> v(1000, structureelement{20, 30}); 

this creates size-1000 vector containing copies of structureelement desired values, seem trying in pseudo-code.

to read elements back, have options. range based for-loop if want iterate on elements:

for (const auto& e: v):   std::cout << e.elem1 << " " << e.elem2 << std::endl; 

using iterators,

for (auto = begin(v); != end(v); ++it)    std::cout << it->elem1 << it->elem2 << std::endl; 

or, pass ranges in algorithms

std::transform(begin(v), end(v), ....);